(1) Field of the Invention
The present invention relates generally to cutterheads for peripheral milling machines, which includes surfacers, planers, molders, joiners and similar machines, and, more particularly, to a substantially helical, stepped blade row cutterhead having removable blade units.
(2) Description of the Prior Art
The present invention relates to improvements in cutterheads, particularly cutterheads such as those shown in the applicant's commonly owned U.S. Pat. Nos. 4,074,737, 5,002,104, 5,653,275, 5,603,365, 5,647,416, and 5,738,156, the entire disclosures of which are incorporated herein by reference in their entirety.
Helical cutterheads for peripheral milling machine that have particular pitch arrangements reduce the noise generated by the cutterhead while planing a workpiece. These cutterheads generally have a plurality of segmented cutterhead inserts, each of which includes a cutting blade mounted in cooperating or receiving grooves in the cutterhead body. In a typical arrangement, the cutterhead inserts span about one inch along the cutterhead length. The cutterhead inserts are securely mounted in the grooves to form substantially continuous blade rows. The contour of the actual cutting edge of the blade rows preferably follows the contour of the helical groove in the cutterhead.
In one embodiment described in the above patents, the cutterhead inserts have carbide cutting blades brazed or welded to them. The carbide blade, after brazing to the cutterhead insert, is subsequently ground to obtain a helical geometry in keeping with the entire helix of the cutterhead. When the cutting blade is worn out, the entire cutterhead insert must be replaced or returned to a tool shop for re-tipping and regrinding.
In the prior art cutterheads, the brazing method of attachment limits the materials that can be used as the cutting blades to those that can withstand brazing, such as conventional carbide. However, more advanced cutting materials including diamonds, ceramics, coated materials, high cobalt alloys, etc. would be difficult to braze and impractical to use as the entire cutterhead insert. The other patents teach various ways to provide removable blade units to in order to eliminate the need for brazing and simplify the re-tipping process, which requires a high degree of skilled labor.
Thus, there still remains a need for an improved cutterhead that permits other blade materials to be used to form the cutting edge while, at the same time, reduces maintenance by eliminating regrinding and providing for simple blade unit replacement as they are worn or damaged.